Apparatus for the production of foamed slabs of rectangular cross section

ABSTRACT

Foam is fed into and forms a loaf in a trough-shaped conveyor whose bottom wall travels lengthwise and entrains a release liner which flanks the loaf from below and at both sides during travel through an elongated foaming station and thereupon through a curing station. The cross-sectional area of an intermediate portion of the conveyor varies gradually and assumes a rectangular outline at least in the downstream part of the foaming station. Such variation in the cross-sectional area is due to changing configuration of the sidewalls and/or to inclination of the bottom wall.

Matted States Patent Heinz Darmochwal Memmingen;

Emil "oxford, Lochham near Munich; Gerhard Muller, Memmlngen; KarHleinz Stelur, Memmingen, all 01, Germany Inventors Appl. No. 745,267 Filed July 16, 1968 Patented Aug. 3, 1971 Assignee Metzeller AG Munich, Germany Priority July 18, 1967 Germany P 17 M 837.2

APPARATUS FOR THE PRODUCTION OF FOAMED SLABS OF RECTANGULAR CROSS SECTION 12 Claims, 33 Drawing Figs.

US. Cl 18/4 B, 18/5 A, 18/5 P Int. Cl 1329c 5/02, B290 5/10 Field oiSmrch 18/4 B,4C,

[56] References Cited UNITED STATES PATENTS 3,123,856 3/1964 Dye et a1 18/4 B 3,124,835 3/1964 Celano et al. 18/4 B 3,240,846 3/1966 Voelker 18/4 (B) X 3,249,486 5/1966 Voisinet et al 18/4 (B) X 3,325,823 6/1967 Boon 18/4 (B) X 3,432,580 3/1969 Heidrich et al. 18/4 (B) X Primary Examiner-J. Spencer Overholser Assistant Examiner-R. L. Spicer, Jr. Att0rneyMichae1 S. Striker ABSTRACT: Foam is fed into and forms a loaf in a troughshaped conveyor whose bottom wall travels lengthwise and entrains a release liner which flanks the loaf from below and at both sides during travel through an elongated foaming station and thereupon through a curing station. The cross-sectional area of an intennediate portion of the conveyor varies gradually and assumes a rectangular outline at least in the downstream part of the foaming station. Such variation in the cross-sectional area is due to changing configuration of the sidewalls and/or to inclination of the bottom wall.

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ATTORN EY APPARATUS FOR THE PRODUCTION OF FOAMED SLABS F RECTANGULAR CROSS SECTION BACKGROUND OF THE INVENTION The invention relates to a method and apparatus for the production of foamed slabs of rectangular cross section. More particularly, the invention relates to a method and apparatus for the production of continuous foamed plastic slabs.

In accordance with presently prevailing practice, a continuous foamed plastic slab of rectangular cross section is formed by pouring the raw material (hereinafter called foam) for slab stock into a stationary trough whose bottom part accommodates a first flexible travelling liner of release paper or the like. Additional travelling flexible liners are provided at the sides of the trough and are disposed in two vertical planes. The lower edges of such additional liners are guided by a plate a portion of which resembles a runner. This runner-shaped portion of the guide plate extends to the upstream end of the foaming station and its configuration is such that the horizontal component of the speed at which the additional liners travel approximates the speed at which the loaf of foam advances in the trough. The vertical component of the speed at which the additional liners advance equals or exceeds the speed at which the load rises during foaming. This is intended to reduce friction between the sides of the load and the sidewalls of the trough and enables the loaf to foam without excessive obstruction and without the formation of a convex top face on the resulting slab.

A drawback of the just-described conventional procedure is that the speed at which the additional liners travel forwardly and upwardly along the sides of the load must be controlled with a high degree of accuracy which necessitates the use of complicated and costly auxiliary equipment and permanent supervision by skilled persons.

It is further known to replace the aforediscussed runnershaped guide plate with rotary disks which flank the sides of the loaf at the foaming station. The angular speed of disks must also be regulated with a high degree of precision and the operation must be supervised at all times.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel and improved method for the production of foamed slabs of rectangular outline in a fully automatic way, with a minimum of supervision, and by resorting to a simple, compact and relatively inexpensive apparatus.

Another object of the invention is to provide a method according to which the fonnation of a continuous foamed slab of rectangular cross section can be controlled automatically with an accuracy unmatched by presently known methods.

A further object of the invention is to provide a novel apparatus for continuous production of foamed slabs of rectangular cross section.

An additional object of the invention is to provide a novel conveyor which can be utilized in the just outlined apparatus to transport a loaf through a foaming station.

A concomitant object of the invention is to provide a conveyor of the just-outlined character which can be used with equal advantage for the production of relatively thin, thick, wide or narrow slabs and which can be used to transport different types of loaves.

The improved method is resorted to in the production of foamed slabs of rectangular cross section, for example, for the production of flexible urethane slab stock or other foam materials produced by similar methods. It comprises the steps of feeding a plastic foam into an elongated confining path wherein the loaf is exposed from above so that it can rise during foaming, which extends through an elongated foaming station and whose crosssectional area varies in and is rectangular at least at the downstream end of the foaming station, i.e., in the region where the loaf is still in a deformable state, conmwamma rmt lnnmhwiqn alone the nnnfinina nath so that the loaf foams and is converted into a slab which is of rectangular outline when it reaches the downstream end of the foaming station, and thereupon curing the resulting slab.

In accordance with one feature of the method, the crosssectional area of the confining path which is defined by a novel conveyor varies at the sides of the advancing loaf and such cross-sectional area preferably varies gradually. In accordance with another feature of the method, the cross-sectional area of the confining path varies also or exclusively at the underside of the travelling loaf and its cross section may remain rectangular all the way from the pouring station to the downstream end of the foaming station. In other words, the cross-sectional area of the path may change by varying the width and/or the depth of the path. When the cross-sectional area varies at the sides of the loaf, it may vary in the upper part or all the way from the bottom to the top zone of the path.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features-and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic longitudinal sectional view of an apparatus which embodies one form of the invention and wherein the sidewalls in an intennediate portion of the conveyor have outwardly flaring platelike top portions;

FIG. 2 is a schematic transverse vertical sectional view as seen in the direction of arrows from the line II-II of FIG. 1;

FIG. 3 is a similar transverse vertical sectional view as seen in the direction of arrows from the line III-III of FIG. 1;

FIG. 4 is a similar sectional view as seen in the direction of arrows from the line IV-IV of FIG. 1;

FIG. 5 is a similar sectional view as seen in the direction of arrows from the line V-V of FIG. 1;

FIG. 6 is a fragmentary transverse sectional view of a second apparatus wherein the intermediate portion of the conveyor comprises side walls of V-shaped cross-sectional outline, this sectional view corresponding to that of FIG. 2;

FIG. 7 is a similar fragmentary transverse vertical sectional view of another portion of the second apparatus and corresponds substantially to the view of FIG. 3;

FIG. 8 is a fragmentary transverse vertical sectional view of a further portion of the second apparatus and corresponds substantially to the view of FIG. 4;

FIG. 9 is a fragmentary transverse vertical sectional view of still another portion of the second apparatus and corresponds substantially to the view of FIG. 5;

FIG. 10 is a schematic transverse vertical sectional view of a first portion of a third apparatus and corresponds substantially to the view of FIG. 2 or 6;

FIGS. 1 l, 12 and 13 are similar transverse vertical sectional views of longitudinally spaced additional portions of the third apparatus and respectively correspond substantially to the views of FIGS. 3, land 5;

FIG. 14 is a schematic transverse vertical sectional view of a fourth apparatus and corresponds substantially to the view of FIG. 2;

FIGS. l5, l6 and 17 are similar transverse vertical sectional views of additional portions of the fourth apparatus and respectively correspond substantially to the views of FIGS. 3, 4, and 5;

FIG. 18 is a schematic transverse vertical sectional view of a fifth apparatus and is similar to the view of FIG. 2;

FIGS. 19, 20 and 21 are transverse vertical sectional views of additional portions of the fifth apparatus and respectively correspond substantially to the views of FIGS. 3, 4 and 5;

FIG. 22 is a schematic transverse vertical sectional view of a sixth apparatus and corresponds substantially to the view of FIG. 2:

FIGS. 23, M and 25 are transverse vertical sectional views of additional portions of the sixth apparatus and respectively correspond substantially to the views of FIGS. 3, 4i and FIG. 26 is a schematic transverse vertical sectional view of a seventh apparatus and corresponds substantially to the view of FIG. 2;

FIGS. 27, 28 and 29 are transverse vertical sectional views of the seventh apparatus and respectively correspond substantially to the views of FIGS. 3, a and 5;

FIG. 311 is a schematic transverse vertical sectional view of an eighth apparatus and corresponds substantially to the view of FIG. 2;

FIGS. 31, 32 and 33 are transverse vertical sectional views of additional portions of the eighth apparatus and respectively correspond substantially to the views of FllGS. 3, ll and 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 to 5, there is shown a first apparatus which may be utilized in the practice of the improved method. The apparatus comprises a feed, for example, one including a conventional traversing mixing head which feeds a plastic foam at a constant rate and continuously into the upstream portion of a conveyor 3 which latter resembles a trough having an open top, two stationary sidewalls 4 and a travelling bottom wall 5, e.g., an endless belt. The thus-admitted foam forms a loaf 1 which is advanced lengthwise in an elongated confining path defined by the conveyor 3 and extending through an elongated foaming station 9.

The trough 3 accommodates a travelling release liner 6 which is made of paper, plastic foil, coated fabric or the like. The release liner 6 may consist of a single sheet which is adjacent to the bottom wall 5 and sidewalls 1 of the conveyor 3, or it may comprise separate panels which are respectively adjacent to each of the sidewalls 4i and bottom wall 5 and are connected to each other by a suitable adhesive. It is also possible to employ a liner which consists of two, four or more panels. The loaf 1 bears against the inner side of the liner 6 and urges it against the adjoining walls of the conveyor 3.

An intermediate portion of the conveyor which begins at or at a certain distance from the pouring station 2 (mixing head 2a) and terminates in the downstream portion 3 of the foaming station 3, is of varying cross section as shown in FIGS. 2 to g The top portions 7 of the sidewalls 41 extend horizontally outwardly in the first or foremost part of the intennediate portion as shown in FIG. 2. The level of the top portions 7 is preferably located in the upper half of the maximum height of the conveyor 3, preferably between the middle and the upper third of such maximum height. The loaf 1 begins to foam during travel with the advancing liner t1 and its height increases which it advances in the foremost part of the intermediate portion of the conveyor 3 so that the foam spills over the top portions 7 in a manner as shown in FIG. 3. In the last third of the foaming station 9, the configuration of the sidewalls 4 changes gradually in that the top parts 7 flex gradually along a helix toward two parallel vertical planes (see FIGS. 41 and 5) to reduce the width of the upper part of the confining path defined by the conveyor 3. The downstream portion of the conveyor 3 (FIG. S) is of rectangular cross-sectional outline and the slab 1a which is obtained on completed foaming of the loaf 1 is also of rectangular outline. The slab 1a is then cured immediately downstream of the foaming station 9.

An important advantage of the sidewalls 41 is that their gradually converging top portions '7 cause the rising loaf l to completely fill the cross-sectional area of the conveyor 3 at the time the loaf is converted into the slab 1a and that the cross section of the resulting slab automatically assumes a rectangular shape and does not have a convex top face. The lateral confinement or reduction of the cross section of the upper part of the rising loaf is gradual in the region beginning at the vertical section line III-III and terminating somewhat bey nd the section line IV-IV of MG. 1.

The sharply defined meeting edges between the vertical lower portions and the outwardly extending top portions 7 of the sidewalls d can be parallel to the plane of the bottom wall 5 or they may be parallel in in the foremost zone of the intermediate conveyor portion and inclined upwardly in the nextfollowing zone of such intermediate portion. The exact construction of the drive for the travelling bottom wall 5 and of the feed (head 2a) forms no part of the present invention. A portion of the drive is shown in FIG. 1 which further shows a source of foam connected to the head 20.

FIGS. 6 to 3 illustrate a portion of a modified conveyor 103 wherein the side walls 104 have a V-shaped cross-sectional outline with their apices facing each other, see F165. 6, 7 and h. in the region where the loaf 1 rises above the apices (FIG. 7) to a desired level, the sidewalls 104 begin to flatten out (i.e., the angle beta between their lower and upper portions inv creases gradually as shown in FIG. 3) and such sidewalls ultimately extend in two parallel vertical planes (FIG. 9).

An important advantage of the conveyor 103 is that, since the friction between the liner 6 and the loaf 1 causes the latter to rise more slowly along the sidewalls 104 than in the central region of the confining path defined by the walls 104, 105, and since the central part of the rising loaf spills over to the sides and also rises beyond the ultimate height of the slab 1a, the descent or collapse of the marginal portions of the loaf (FIG. 3) along the sidewalls we is slower (due to friction) than in 'the central part which results in the production of a slab 1a of rectangular cross section (FIG. 9) with a flat top face.

FIGS. 10 to 13 illustrate portions of a third conveyor 203 wherein the top portions 210 of the sidewalls 2M first extend inwardly (FIG. and thereupon flare gradually outwardly (FIGS. 11 and 12) to ultimately reach two parallel vertical planes (FIG. 13). The maximum angle alpha between the top portions 2111 and the imaginary extension of the vertical lower portions of the respective sidewalls 2114 is preferably between 30 and 40. The loaf 1 foams while it travels between the sidewalls 2M and rises between the inwardly extending top portions 210. In the region where the height of the loaf 1 reaches a desired level, the top portions 210 begin to change their inclination gradually (the angles alpha decrease). Here, too, the height of the loaf 1 rises along the top portions 210 to a level above the ultimate height of the slab and thereupon decreases at a lesser rate than in the center of the loaf so that the ultimate product is a slab of rectangular cross section (FIG. 13) with a flat top face. During foaming, the height of the central portion of the loaf initially rises to a level above the maximum level of foam along the top portions 210; however, the central part thereupon collapses more rapidly than along the sidewalls 21%. This is due to friction between the side panels of the liner 6 and the adjoining portions of the loaf. The numeral 203 denotes the travelling bottom wall of the conveyor 2113.

Theconveyor 303 of FIGS. 14 to 17 comprises sidewalls 311d having concave-convex top portions 331 in the intermediate portion of the conveyor (FIGS. 14-16) whereby the convex sides of such portions 3 3 face each other. The effect of sidewalls 304 on the formation of a slab 111 (FIG. 17) of rectangular outline is similar to the effect of side walls 4 shown in FIGS. 1 to S. The bottom wall of the conveyor 303 is shown at 3055 and the liner is shown at 6. The numeral 1 denotes the loaf.

In the conveyor 4103 of FIGS. 13 to 21, the entire sidewalls 412 in the intermediate portion of the conveyor are of concave-convex shape (FIGS. 13-20) with gradual transition into a pair of parallel vertical planes (FIG. 21). The numerals ll, Ila, (W5 and 6 denote parts similarly identified in the preceding Figures. The top edges of the sidewalls 4112 may be parallel with and/or inclined with reference to the bottom wall 4105. The same holds true for the sidewalls 30d.

FIGS. 22 to 25 show a conveyor 503 whose sidewalls 513 are of semicircular cross-sectional outline in the intermediate portion of the conveyor. The effect of sidewalls 513 in the formation of a slab 1a (FIG. 25) of rectangular cross section 6 -9. The travelling bottom wall of the conveyor 503 is shown in FIGS. 26 to 29, the intermediate portion of the conveyor 603 comprises sidewalls 604 having top portions 611 of concave-convex cross-sectional outline but with the concave sides facing the loaf 1. The effect of such sidewalls on the formation of a slab la (H6. 29) of rectangular cross-sectional outline is similar to that of the sidewalls 204 shown in FIGS. 10-43. The bottom wall of the conveyor 603 is shown at 605.

N68. 30 to 33 show a conveyor 703 having sidewalls 714 of concave-convex cross-sectional outline. The efi'ect of such sidewalls on the formation of a rectangular slab 111 (FIG. 33) which travels with the bottom wall 705 is similar to that of sidewalls 604. An advantage of the modifications shown in FIGS. 14-33 is that the liner 6 is less likely to be damaged or destroyed because the zones of transition between the upright lower and the curved upper portions of sidewalls (FIGS. 14- 17 and 26-29) or the entire sidewalls (FIGS. 18-25 and 30-33) are curved.

An advantage of each of the aforedescribed apparatus is that they can produce a slab having a flat top surface and that this is insured with minimal outlay for auxiliary equipment. Thus, the guide plates and rotary disks which are essential parts of conventional apparatus can be dispensed with. The liners need not be advanced upwardly at the rate at which the loaf rises in the foaming station. Also, the speed of the liners invariably equals the speed of the loaves and such liners are transported at the desired speed by the travelling bottom walls of the respective conveyors.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of the above outlined contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What We claim as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. Apparatus for producing foamed slabs of rectangular cross section, comprising an elongated conveyor having an open top and including an upstream portion, a downstream portion of substantially rectangular cross-sectional outline and an intermediate portion, said conveyor having a travelling bottom wall and sidewalls extending along said bottom wall, at least a portion of each of said sidewalls in the intermediate portion of said conveyor being inclined with reference to a vertical plane and the inclination of such portions of said sidewalls decreasing successively to zero in a direction toward said downstream portion of said conveyor; and a feed for continuously supplying plastic foam to said upstream portion whereby such foam forms a continuous loaf which advances lengthwise through said intermediate portion and is foamed to form a slab of rectangular outline on entry into said downstream portion.

2. Apparatus as defined in claim 1, further comprising a release liner coating said conveyor and extending along the underside and the lateral sides of the loaf in said conveyor and sharing the lengthwise movement of the loaf.

3. Apparatus as defined in claim 1, wherein at least a portion of each of said sidewalls is of arcuate cross-sectional outline in said intermediate portion of the conveyor.

4. Apparatus as defined in claim 3, wherein each of said sidewalls is of arcuate cross-sectional outline all the way to said bottom wall.

5. Apparatus as defined in claim 3, wherein said portions of said sidewalls have facing convex surfaces.

6. Apparatus as defined in claim 3, wherein said portions of said sidewalls have facing concave surfaces.

7. Apparatus as defined in claim 1, wherein said sidewalls have mutually inclined upper and lower portions in the intermediate portion of said conveyor and wherein such mutually inclined portions have sharply defined meeting edges.

8. Apparatus as defined In claim 7, wherein at least a portion of each of said meeting edges is substantially parallel to said bottom wall.

9. Apparatus as defined in claim 7, wherein at least a portion of each of said meeting edges is inclined with reference to said bottom wall.

10. Apparatus as defined in claim 1, wherein at least the upper portion of each of said sidewalls is of arcuate cross-sectional outline in said intermediate portion of said conveyor and wherein said upper portions include top edges at least a portion of each of which is substantially parallel to said bottom wall.

11. Apparatus as defined in claim 1, wherein at least the upper portion of each of said sidewalls in the intermediate portion of said conveyor is of arcuate cross-sectional outline and wherein said upper portions have top edges at least a portion of each of which is inclined with reference to said bottom wall.

12. Apparatus as defined in claim 1, wherein said sidewalls in the intermediate portion of said conveyor are of V-shaped cross section and having apices which face each other. 

1. Apparatus for producing foamed slabs of rectangular cross section, comprising an elongated conveyor having an open top and including an upstream portion, a downstream portion of substantially rectangular cross-sectional outline and an intermediate portion, said conveyor having a travelling bottom wall and sidewalls extending along said bottom wall, at least a portion of each of said sidewalls in the intermediate portion of said conveyor being inclined with reference to a vertical plane and the inclination of such portions of said sidewalls decreasing successively to zero in a direction toward said downstream portion of said conveyor; and a feed for continuously supplying plastic foam to said upstream portion whereby such foam forms a continuous loaf which advances lengthwise through said intermediate portion and is foamed to form a slab of rectangular outline on entry into said downstream portion.
 2. Apparatus as defined in claim 1, further comprising a release liner coating said conveyor and extending along the underside and the lateral sides of the loaf in said conveyor and sharing the lengthwise movement of the loaf.
 3. Apparatus as defined in claim 1, wherein at least a portion of each of said sidewalls is of arcuate cross-sectional outline in said intermediate portion of the conveyor.
 4. Apparatus as defined in claim 3, wherein each of said sidewalls is of arcuate cross-sectional outline all the way to said bottom wall.
 5. Apparatus as defined in claim 3, wherein said portions of said sidewalls have facing convex surfaces.
 6. Apparatus as defined in claim 3, wherein said portions of said sidewalls have facing concave surfaces.
 7. Apparatus as defined in claim 1, wherein said sidewalls have mutually inclined upper and lower portions in the intermediate portion of said conveyor and wherein such mutually inclined portions have sharply defined meeting edges.
 8. Apparatus as defined in claim 7, wherein at least a portion of each of said meeting edges is substantially parallel to said bottom wall.
 9. Apparatus as defined in claim 7, wherein at least a portion of each of said meeting edges is inclined with reference to said bottom wall.
 10. Apparatus as defined in claim 1, wherein at least the upper portion of each of said sidewalls is of arcuate cross-sectional outline in said intermediate portion of said conveyor and wherein said upper portions include top edges at least a portion of each of which is substantially parallel to said bottom wall.
 11. Apparatus as defined in claim 1, wherein at least the upper portion of each of said sidewalls in the intermediate portion of said conveyor is of arcuate cross-sectional outline and wherein said upper portions have top edges at least a portion of each of which is inclined with reference to said bottom wall.
 12. Apparatus as defined in claim 1, wherein said sidewalls in the intermediate portion of said conveyor are of V-shaped cross section and having apices which face each other. 